A retardation film such as a quarter-wave plate that converts linearly polarized light into circularly polarized light, or a half-wave plate that converts the plane of vibration of linearly polarized light by 90°, has been widely used for a flat panel display and the like.
However, a known retardation film has a problem in that polarized light that passes through the retardation film is converted into colored polarized light. In order to solve the above problem, various wideband retardation films that can achieve uniform retardation for light over a wide wavelength band (i.e., retardation films having reverse wavelength dispersion) have been studied (see Patent Documents 1 to 6).
It has been desired to reduce the thickness of a flat panel display as much as possible along with an improvement in performance and widespread use of mobile information terminals (e.g., mobile personal computer and mobile phone). Therefore, a reduction in thickness of the retardation film has also been desired. It has been considered that the thickness of the retardation film can be most effectively reduced by producing the retardation film by applying a polymerizable composition that includes a low-molecular-weight polymerizable compound to a film substrate. Low-molecular-weight polymerizable compounds having excellent wavelength dispersion and polymerizable compositions using such polymerizable compounds have been proposed (see Patent Documents 7 to 24).
Patent Document 25 discloses a dihydroxy compound that has a structure similar to that of the compound according to the invention. However, Patent Document 25 does not disclose the compound according to the invention. Moreover, the compound disclosed in Patent Document 25 is used as a drug (i.e., enhancers of protein degradation).